Buckle for seat belts



Oct. 10 1967 $M|TH ET AL 3,345,712

BUCKLE FOR SEAT BELTS Filed Feb. 21, 1966 2 Sheets-Sheet 1 Y I I 1 i 7:l l I l I! 12H i I Z H INVENTORS I6 32 65mm J. PARTRIDGE LAWRENCE H-SMITH ATTORNEYS Oct. 10 1967 5M|TH ET AL BUCKLE FOR SEAT BELTS FiledFeb. 21, 1966 2 Sheets-Sheet 2 INVENTORS GERALD J. PARTRIDGE. LAWRENCEH. SMITH.

ATTORNEYS United States Patent 3,345,712 BUCKLE FOR SEAT BELTS LawrenceH. Smith, Bloomfield Hills, and Gerald J. Partridge, Detroit, Mich.,assignors to Jim Robbins Seat Belt (10., Royal Oak, Mich.

Filed Feb. 21, 1966, Ser. No. 528,876 Claims. (Cl. 24230) This inventionrelates to a buckle for releasably securing the ends of two beltsections of a vehicle safety seat belt system and more particularly to abuckle of the type termed metal-to-meta wherein a male tongue member issecured to the end of one belt and a buckle member secured to the otheris adapted to releasably retain the tongue member.

The buckle of the present invention is of the type which automaticallylocks the tongue in the buckle when the tongue is manually insertedthrough one side wall thereof and wherein the tongue may be releasedfrom the buckle by pressing a pushbutton formed in the outer surface ofthe buckle. While buckles of this type have been previously proposed,the present buckle structure is particularly convenient to use andtrouble-free in operation as well as being simple so as to be economicalto manufacture and highly reliable in operation.

As disclosed in the following detailed description of a preferredembodiment of the invention, the tongue member fitted to one of the beltends consists of a flat section having a slot adjacent to its extremeend which extends transversely to the length of the belt. The tongue isadapted to be inserted into the base of the other buckle member. Thebase consists of a fiat bottom with a pair of upturned side walls. Theside walls pivotably support a latching member having a lock sectionadapted to enter the slot in the tongue in order to retain the tonguewithin the base member. A spring biases the latch member into thisdownward, locked position and allows the latch member to be rocked intoan unlocked position by the end of the tongue member as it is pressedinto the buckle. When the latch member is in its closed position, withits lock section extending into the slot in the tongue, any retractingforce exerted on the tongue simply tends to urge the latch memberfurther in its locking direction. In order to open the belt, the latchmember is pivoted out of its locked position by depressing a pushbuttonslidably supported in a cover member for the base. The cover memberextends over the top and sides of the base and provides a slot at oneend for the entrance of the tongue member.

The pushbutton motion is transmitted to the latch member by a cam andlever arrangement which includes a cylindrical rod that extends acrossthe width of the base and has a pair of cylindrical pins, smaller indiameter than the rod, projecting outwardly from the ends of the rod,with their axes displaced with respect to the central axis of the rod soas to act as eccentrics. These eccentric pins are rotatably supported bythe upturned sides of the base. Accordingly, when the transverse rodrotates about its end pins, it does so in an eccentric manner. Thetransverse rod itself passes through a pair of holes formed in opposedpoints in upturned sidewalls of the lock member. These holes are justlarge enough to allow a rolling fit to the rod. An elongated lever isconnected to one edge of the rod and has its other end abutting thelower side of the pushbutton. This allows the downward movement of thepushbutton to be converted into a rotation of the lever. When thepushbutton is depressed, the lever causes the rod to rotate in aneccentric manner about its end pins, so as to cause the latching memberto rotate, in the manner of a cam, about its pivot point. This raisesthe lock section of the latching member allowing the belt tongue to bewithdrawn. The extension of the lever arm between the center of thetransverse rod and its contact point with the pushbutton is severaltimes longer than the eccentric distance between the pins and the centerof the rod, so as to provide a mechanical advantage to the openingaction and also to require a relatively large button movement beforeopening will occur. The mechanical advantage tends to insure that thebuckle will open after it has been subjected to heavy stresses, such asmight occur in an accident, and represents an important safety feature,since if the buckle would not open after anaccident, the occupant of theseat may be trapped therein. The relatively large pushbutton movementbefore the buckle opens insures against accidental opening of thebuckle. The upper surface of the button is recessed within the buckletop to provide additional assurance that an accidental force on the topwill not depress the button.

It is therefore seen to be a primary object of the present invention toprovide a simple and reliable construction for a belt retaining bucklewherein a spring biased latch member having a locking section whichenters a slot in the buckle tongue may be released by a pushbutton whichtransmits its motion to the latch member by a lever and cam arrangementwhich increases the force and decreases the movement of the pushbuttonmotion when applying it to the latch.

Another object is to provide such a buckle wherein the latch member ispivotably supported with respect to the base member and is alsorotatably supported with respect to a circular cam member, which isitself supported with respect to the base along an axis eccentric to itsaxis of support of the latch member, and means are provided for rotatingthe cam member as the pushbutton is depressed.

A further object is to provide such an arrangement wherein the cammember is rotated by a lever arm abutting the under side of thepushbutton and the length of the lever arm exceeds the eccentricdistance of the cam so as to provide a mechanical advantage to the forceexerted to lift the latch member.

Other objects, advantages and applications of the present invention willbe made apparent by the following detailed description of a preferredembodiment to the invention. The description makes reference to theaccompanying drawings in which:

FIGURE 1 is a top view of a buckle formed in accordance with the presentinvention along with the ends of its associated belt webbings;

FIGURE 2 is an elevation sectional view through the structure of thebuckle taken along line 22 of FIG- URE 1;

FIGURE 3 is a plan view through the buckle with the cover memberremoved;

FIGURE 4 is a perspective view of the buckle and the retracted tonguewith the cover again removed for purposes of illustration; and

FIGURE 5 is an elevation sectional view through the buckle assemblywhile the button is in a depressed condition taken along line 22 ofFIGURE 1.

Referring to the drawings, the buckle of the present invention isapplied at the ends of a pair of webbing sections 10 and 12. Theopposite ends of the webbing section are appropriately connected to theframe of the vehicle in which the belt system is employed so that whenthe two buckle sections are joined together a closed loop is formedsecurely retaining the occupant in his seat. The belt section 12 isjoined to a main buckle member generally indicated at 14 in a mannerwhich will be subsequently described. The belt section 112 is joined toa tongue member, generally indicated at 16 which is adapted to be lockedwithin the buckle 14.

The tongue section 16 is formed of a relatively thin, flat metal plate,generally rectangular in shape, and having a widened section 18 at oneend formed with a slot 20 across its width. A loop 22 is formed at theend of the belt 12 and is appropriately joined to the main belt section,as by sewing, in order to retain the tongue member 16 on the end of thebelt 12. The forward end of the tongue 16 has rounded corners 24 and hasa second, rectangular slot 26 formed across its width.

The main buckle member 14 is formed about a base member 28 which has apair of opposed upturned sides 30 and 32 which extend generally normallyto the base. The base member and sides are preferably stamped out ofhigh tensile alloy steel. At the end of the base member, adjacent to thebelt (which will be termed the rear end of the base), the side walls 30and 32 are obliquely pierced at opposed points to form slots 34. Aserrated roller 36, having a length slightly less than the distancebetween the interior opposed sides of the walls 30 and 32, is supportedin the slots by means of extending rectangular tabs 38 which projectfrom its ends into but not through the slots. The tabs 38 are shorterand thinner than the slots so that the roller 36 may slide along theslots. The base 28 has a section 40 punched out of its bottom whichallows the belt 10 to be brought up through the hole 40, brought aroundthe roller 36, and returned through the slot. In this manner when a pullis exerted on the belt 10, the roller 36 tends to move downwardly in theslot 34 and thus lock the belt 10 to the buckle section 14 againstretraction.

The forward end of the punched out section 40 is bent upwardly andforwardly into a tab 42 which acts as a stop for the forward end of thetongue 16 when that is inserted into the base. As may be best seen inFIGURE 2, the tongue is locked into the base by means of a latch membergenerally indicated at 44.

The latch member 44 is formed of a sheet of metal having a pair ofupturned sides 46. The distance between the outer surfaces of theupturned sides 46 is slightly less than the distance between theinternal surfaces of the sides 30 and 32 of the base so that the latchmember may be supported between the sides 30 and 32 with its surfaces 46adjacent to the interior sides of the members 30 and 32.

A shaft 48 has its opposite ends fixed within holes pierced in opposedpoints on the sides 30 and 32 adjacent to the forward ends thereof. Theshaft extends laterally across the width of the base and passes througha pair of holes formed in the sides 46 of the latch so as to rotatablysupport the latch with respect to the base.

The latch member 44 has a forward section 58 which is bent generallyupward with respect to the base 28. so that the tongue 16 may be easilyinserted under the latch member by pressing it against the lower end ofthe section 58. The latch member has a downwardly bent locking tab 60pierced out of and extending from its intermediate section which isnormally disposed with its lower end just above the base member 28.

' The base is surrounded on its top and sides by a cover membergenerally indicated at 70 preferably formed of plastic and beinggenerally rectangular in shape with a closedtop 72 and four downwardlyprojecting sides 74. The front side of the cover is cut away as at 75and four downwardly projecting sides 74. The front side of the cover iscut away as at 75 to allow the tongue to be inserted in the bucklemember and the remaining front of the cover prevents the tongue frombeing accidentally inserted over the top of the latch section 58 andgiving a false latch condition. The cover passes over the side membersof the base 30 and 32 and snaps thereon by means of a protrusion 76which extends inwardly from the top sides and mates with recesses 78formed on the rear ends of the side plates 30 and 32. The fit of thetabs in the recesses allows the cover to be pressed over the sides ofthe base member and locked in position and it may be removed forinspection by pulling the 4 downwardly turned rear end of the cover 70away from the sides 30 and 32.

A rectangular aperture 80 is formed in the top of the cover memberadjacent to its front end. A plastic pushbutton 86 having outerdimensions which are complementary to the aperture 80 is disposedtherein. The planar surface of the pushbutton 86 is surrounded by adownturned edge 88 and which fits within the side walls 84 of theaperture. The tabs 90 extend from the four corners of the sides of thepushbutton 86 in sideward directions and are journaled in appropriateslots formed in the side surfaces of the downturned edge 84. These slotsguide the pushbutton for vertical motion within the aperture 80 and theupper ends of the slots limit the upward movement of the pushbuttonwithin the aperture.

A coiled compression spring 94 is secured between the cover top 72 andthe latch member 44. The lower end of the spring 94 is retained by anupwardly extending tab 96 which projects from the rearward end of thelatch member 44 and is seated within the interior diameter of thespring. The upper end of the spring '94 is retained by a projection '98which extends downwardly from the top 72 of the cover member and isseated in the ID. of the spring at its upper end. The spring tends torotate the latch member 44 in a counter-clockwise direction as viewed inFIGURES 2 and 5, into what will be termed a locked position wherein thelocking tab 60 is in close proximity to the upper surface of the basemember 28.

When the tongue member 16 is inserted through the opening 75 in thecover and under the uplifted section 58 of the latch member, its forwardend abuts the bottom of the locking tab 60 and tends to rotate the latchmember in a clockwise direction so as to lift the lock member 60 andallow the tongue member to be inserted against the stop 42. When in thisposition, the locking tab 60 is in position over the slot 26 in thetongue and enters that slot allowing the latch to rotate, under thespring bias, into its locked position which is shown in FIGURE 2.

In order to release the tongue member, pressure is put on the pushbutton86 and its motion is communicated to the latch member through acam-lever arrangement which is built about a transversely extending camrod 100. The rod 100 is circular in cross section and has a lengthapproximately equal to the distance between opposed inner faces of theside walls 30 and 32 of the base. It passes through a pair of holes 102formed in opposed points on the upturned side walls 46 of the, latchmember 44. The holes 102 are slightly larger than the diameter of therod 100, making a loose sliding fit therewith.

The two ends of the rod 100 have projecting eccentric pins 104 formedthereon. The pins are cylindrical and are both formed about an axiswhich is displaced with respect to the central axis of the rod 100.

The pins 104 are journaled in slots 106 formed in opposed points on theside walls 30 and 32 of the base. The slots 106 are formed from theupper edge of the side walls and extend slightly less than half way downtheir depth. Their lower edges are rounded to approximately the samediameter as the pins 104. The distance between the outer ends of theeccentric pins 104 is equal to that between the outer walls of the sidewalls 30 and 32 so that the pins lay in the side walls without extendingappreciably beyond them.

A generally flat, elongated lever member 110, formed out of sheet steel,has one of its ends disposed in a shallow slot 112 formed in one side ofthe center of the rod 100, and is retained within the slot as bywelding. The lever 110 has a central stamped depression 114, formed forstifiening purposes. It is generally straight along its length and itsend opposite to that which is retained to the rod 100 is curveddownwardly as at 116.

The angle and position of the slot 112 with respect to the rod 100 issuch that the lever 110 extends upwardly in an inclined angle, so thatthe upper convex side of the curved end 116 abuts the lower end of thepushbutton 80. In this manner, the spring 94 acts through the latchmember 44 and the lever 110 to normally maintain the pushbutton 86 atits extreme upper position. In this position, it is just below the topsurface of the cover.

When the pushbutton is depressed by applying a force to its uppersurface, it tends to press the lever 116 of the lever 110 downwardly.The convex curvature of the upper end of the lever acts to smoothlytransfer the downward motion of the pushbutton into a rotation of thecam. This rotation is transferred to the rod 100 and the eccentric pins104 act as its center of the rotation. The resultant eccentric rotationof the rod 100 tends to rotate or lift the latch member in a clockwisedirection as viewed in FIGURES 2 and 5, because of the extension of therod 100 through the holes 102 in the sides of the latch member. Thisacts to lift the locking tab 60 out of the slot 26 and to free thetongue 16 for retraction. This action is performed against the bias ofthe spring 94 which is compressed as a result of the tab 106 liftingduring the rotation of the latch member.

The cam 100 and lever 110 act together as a lever of the first class,that is, one point of application of the force 116, is on the first sideof the fulcrum (the journal of the pins 104 in the bottom of the slots106), and the second point of force application defined by the center ofthe rod 100 within the holes 102, is on the other side of this fulcrum.Because the distance between the fulcrum and the end 16 is larger thanthe distance between the fulcrum and the center of the rod 100, amechanical advantage is realized and the force exerted downwardly on thepushbutton results in a proportionally higher force on the lifting tab.Conversely, a relatively long downward motion of the pushbutton resultsin a relatively short motion of the latch member. Thus, a relativelylarge downward motion of the push'buttton is required to lift the lockmember to allow the tongue to be retracted, obviating the possibility ofa slight accidental deflection of the pushbutton allowing the unit tobecome unlocked. The relatively high force applied to the latchincreases the probability that the buckle will be able to open after theimposition of stress forces as a result of an accident. A standard testwhich is applied to such belts is to determine if they open aftertension forces in excess of the rated strength of the buckle have beenapplied to the belts. The force multiplication arrangement has beenfound to easily allow buckles formed in accordance with the presentinvention to pass such tests.

It is thus seen that the tongue may be easily locked in the buckle andsecurely retained therein until a definite force, acting through afairly large distance, depresses the pushbutton so as to rotate thelatch out of its locked position.

Having thus described our invention, we claim:

1. A seat belt buckle of the type described, comprising: a base having aplanar surface; a latch member pivotably supported with respect to thebase for rotation about an axis extending parallel to and transverselyacross the base; a locking section on the latch member adapted to extendadjacent to the base at one extreme rotation of the latch member; springmeans biasing said latch member toward said extreme rotation; apushbutton supported with respect to the base for motion toward and awayfrom said planar surface; a cam having an eccentric section rotatablysupported with respect to the base, said eccentric section movablyengaging said latch member in such a manner as to pivot the latch memberagainst the bias of the spring means so as to move the locking sectionaway from the base, at such time as the cam is rotated; and means,disposed between the pushbutton and the cam and movable with respect tosaid pushbutton, operative to cause the cam to rotate as the pushbuttonis moved toward the base.

2. A seat belt buckle of claim 1 wherein the means for causing the camto rotate as the pushbutton is moved toward the base consists of anelongated lever having a first end connected to the cam and a second endabutting the pushbutton so that said second end is moved toward the baseas the pushbutton is moved toward the base, thereby rotating said cam.

3. The seat buckle of claim 2 wherein the lever is connected to the camat a point separated from its axis of rotation and is connected to thepushbutton by abutting the underside thereof.

4. The seat belt buckle of claim 3 wherein the cam is supported forrotation with respect to the base about a first axis extending parallelto the base and is connected to the latch member by means of saideccentric section which is journaled within said latch member.

5. The seat belt buckle of claim 4 wherein the base has a pair ofupturned sides which rotatably journal the cam and the latch member hasa pair of upturned sides which are disposed between the sides of thebase and which have holes formed which journal the eccentric section ofsaid cam.

6. The seat belt buckle of claim 5 wherein the pushbutton is supportedfor rotation in a cover member which has a generally flat top with anaperture formed therein for the pushbutton and at least one pair ofdownturned sides which are adapted to be dispose-d on the outer sides ofthe upturned sides of the base.

7. The seat belt buckle of claim 6 wherein the spring means for biasingthe latch member constitutes a coiled compression spring supportedbetween a surface of the latch member and the opposed undersurface ofthe cover member.

8. The seat belt buckle of claim 2 wherein the distance between thepoint of abutment of the pushbutton with the lever and the axis ofrotation of the cam is greater than the distance between the connectionof the cam to the latch member and the axis of rotation of the cam,whereby a relatively large movement of the pushbutton results in arelatively small movement of the latch member.

9. The seat belt buckle of claim 1 wherein the cam is rotatablysupported with respect to the base about an axis which extends parallelto the base, and said eccentric section is rotatably supported in thelatch member.

10. The seat belt buckle of claim 9 wherein the con nection between thecam and the pushbutton is made by a lever member having one end fixed tothe cam and the other end in abutment to the pushbutton.

References Cited UNITED STATES PATENTS 2,995,792 8/ 1961 Morton.

3,189,966 6/1965 Craven.

3,203,064 8/ 1965 Murphy.

3,242,547 3/ 1966 Krengel.

3,270,388 9/ 1966 Humphrey.

BERNARD A. GELAK, Primary Examiner.

1. A SEAT BELT BUCKLE OF THE TYPE DESCRIBED, COMPRISING: A BASE HAVING APLANAR SURFACE; A LATCH MEMBER PIVOTABLE SUPPORTED WITH RESPECT TO THEBASE FOR ROTATION ABOUT AN AXIS EXTENDING PARALLEL TO AND TRANSVERSELYACROSS THE BASE; A LOCKING SECTION ON THE LATCH MEMBER ADAPTED TO EXTENDADJACENT TO THE BASE AT ONE EXTREME ROTATION OF THE LATCH MEMBER; SPRINGMEANS BIASING SAID LATCH MEMBER TOWARD SAID EXTREME ROTATION; APUSHBUTTON SUPPORTED WITH RESPECT TO THE BASE FOR MOTION TOWARD AND AWAYFROM SAID PLANAR SURFACE; A CAM HAVING AN ECCENTRIC SECTION ROTATABLYSUPPORTED WITH RESPECT TO THE BASE, SAID ECCEN-